> From: Dave Emery[SMTP:[EMAIL PROTECTED]]
>
> On Wed, May 30, 2001 at 08:34:28AM -0700, Steve Schear wrote:
> > At 06:57 AM 5/30/2001 +0000, Dr. Evil wrote:
> > >And also, yes, the CIA direction finding stuff apparently wasn't
> > >working there. Oh well, starting in October all cellphones will have
> > >GPS built in, which will take all the guesswork out.
> >
> > Which can be easily jammed by a handi-dandi Hyde 'n Seek (tm) GPS
> > transmitter fob near your cell phone antenna.
>
> While that is certainly true (and real low power 1574.2 mhz
> jammers aren't that hard to make), it is by no means true that most
> cellphone location will be done via GPS. Several of the carriers have
> filed for use of various differential time of arrival/ angle of arrival
> systems which work with current cellphones and do not require upgrades
> of customer equipment (thus avoiding the issues involved in ensuring
> that enough customers have upgraded handsets to meet FCC penetration
> requirements).
>
> > steve
>
The easiest way to defeat GPS is to walk indoors.
Unless GPS technology has made great strides in the last couple of years,
I find the GPS-in-cellphone technology claims a little dubious. I've been
using
a Garmin GPS III+ for a couple of years. This is (was) a fairly high-end
outdoor model - it cost about $300. It's built like a tank, and all the
components
are of high quality, including the fat, stubby antenna.
Walk into any building with construction more sturdy than a wood frame, and
the signal is lost. Remember, it's trying to pick up at least four low-power
satellites which are at least several hundred miles away. Even heavy, wet
foliage can significantly impact it's reception. In city streets it's not
very
reliable, and inside a steel frame building its hopeless.
This, in a high-end, purpose-built GPS unit. I find it doubtful that even
this
level of performance can be added to a cellphone and keep the price at
a reasonable level.
By the way, Garmin does make one cellphone with built in GPS:
http://www.garmin.com/products/navTalkPilot/
it costs about $425.
Peter Trei
